CVE-2026-64416: mm: swap_cgroup: fix NULL deref in lookup_swap_cgroup_id on swapless host
Vulnerability summary
CVE-2026-64416 is a medium (CVSS 5.5) NULL Pointer Dereference vulnerability in linux. EPSS estimates a 0.12% chance of exploitation in the next 30 days, higher than 1.9% of scored vulnerabilities.
Not severe (CVSS 5.5, local access); no exploitation reported by the 5 checked sources
Source freshness unavailable
How is this decided?Advisory lineage
Upstream 0 · Downstream 17 · Related 17Timeline
- 25-07-2026PublishedVulnerability first disclosed.
- 17-08-2026Last modifiedVulnerability information updated.
Description
In the Linux kernel, the following vulnerability has been resolved: mm: swap_cgroup: fix NULL deref in lookup_swap_cgroup_id on swapless host lookup_swap_cgroup_id() passes swap_cgroup_ctrl[type].map to __swap_cgroup_id_lookup() without checking that the type was ever registered via swap_cgroup_swapon(). On a swapless host every ctrl->map is NULL, so __swap_cgroup_id_lookup() dereferences NULL + a scaled swp_offset(). Since commit bea67dcc5eea ("mm: attempt to batch free swap entries for zap_pte_range()"), zap_pte_range() -> swap_pte_batch() calls lookup_swap_cgroup_id() on any non-present, non-none PTE that decodes as a real swap entry, without first validating it against swap_info[]. A single PTE corrupted into a type-0 swap entry takes the host down at process exit. We hit this in production on a swapless 6.12.58 host: ~1s of "get_swap_device: Bad swap file entry 3f800204222bb" (do_swap_page() being correctly defensive about the same entry) followed by BUG: unable to handle page fault for address: 000003f800204220 RIP: 0010:lookup_swap_cgroup_id+0x2b/0x60 Call Trace: swap_pte_batch+0xbf/0x230 zap_pte_range+0x4c8/0x780 unmap_page_range+0x190/0x3e0 exit_mmap+0xd9/0x3c0 do_exit+0x20c/0x4b0 syzbot has reported the identical stack. The source of the PTE corruption is a separate bug; this change makes the teardown path as robust as the fault path already is. Every other caller of lookup_swap_cgroup_id() is downstream of a get_swap_device() that has already validated the entry, so the new branch is cold.
CVSS metrics
3 scores · 3 sources · 1 version- OSV · UbuntuEcosystem advisory · calculated5.5MediumCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
- OSV · DebianEcosystem advisory · calculated5.5MediumCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
EPSS trend
Probability
0.12%
Chance of exploitation in the next 30 days
Percentile
2%
Versus all other CVEs
30-day change
No change 0.00 pp
From 0.12% on 04-10-2026
Known exploited
Compare KEV catalogs
CISA KEVNot in the CISA KEV catalog.
ENISA CNWNot in the ENISA CNW catalog.
CIRCLNot in the CIRCL catalog.
Public exploits
0 foundNo public exploits indexed.
Weaknesses
CWE · root causeAffected systems
Known conditions: local access, low-privilege account, no user interaction (CVSS vector). Other conditions: not stated in public data.
Ubuntu119 products
- linux< 7.0.0-31.31
- linux-allwinner-5.19All versions (No fix recorded)
- linux-aws< 7.0.0-1012.12
- linux-aws-5.0All versions (No fix recorded)
- linux-aws-5.11All versions (No fix recorded)
Debian2 products
- linux< 6.12.100-1 | < 7.1.4-1
- linux-6.12< 6.12.100-1~deb12u1
Linux2 products
- linux≥ bea67dcc5eea0f6a213897a59b9e644977cd07e6, < 818416fef38759f23210de449663cd9d7e293d39 | ≥ bea67dcc5eea0f6a213897a59b9e644977cd07e6, < b415c00bf23df577a4a95673d00ae76687bcc1d4 | ≥ bea67dcc5eea0f6a213897a59b9e644977cd07e6, < 6a4196d19f477524d2f92adca90fc1fbe9a0420a | ≥ bea67dcc5eea0f6a213897a59b9e644977cd07e6, < 63b02a9409cb5180398491b093e48bcb5315f5fb | 6.12
- linux_kernel≥ 6.12, < 6.12.97 | ≥ 6.13, < 6.18.39 | ≥ 6.19, < 7.1.4
3 vendors · 123 products
